Natural Communities of NH -- Photo Guide

Red oak - ironwood - Pennsylvania sedge woodland  (S2)



Red oak - ironwood - Pennsylvania sedge woodland
is an uncommon natural community type of open ridges and upper slopes of hills and low mountains in central and southern New Hampshire. It is notable for the “grassy” lawn of Pennsylvania sedge (Carex pensylvanica) that carpets the ground, the semi-open, park-like nature of the tree canopy, and a variety of rich-site herbs. Elevations range from 400-1,600 ft. in known examples.

Soils are often thin, rocky loam or sandy loams derived from intermediate, base-rich, or mafic bedrock (including syenite, diorite, and diabase). Soil moisture ranges from dry to dry-mesic. These enriched sites may cover many acres, or may correspond to small areas within larger, acidic rocky ridge or forest communities.

Characteristic Vegetation: Characteristic trees include red oak (Quercus rubra), shagbark hickory (Carya ovata), white ash (Fraxinus americana), sugar maple (Acer saccharum), ironwood (Ostrya virginiana), and white pine (Pinus strobus). The dense lawns of Pennsylvania sedge (Carex pensylvanica) are diagnostic of somewhat enriched conditions and help distinguish this community from rich Appalachian oak rocky woods. Distant sedge (Carex lucorum) is a species very similar to Pennsylvania sedge; it may be found in this community, but typically occurs on nutrient-poor sites such as acidic rocky ridges and sandy soils.

Other Herbs that are characteristic of rocky ridges in general are common and include wood anemone (Anemone quinquefolia), wild columbine (Aquilegia canadensis), common hair-grass (Deschampsia flexuosa), rough-leaved rice-grass (Oryzopsis asperifolia), pussytoes (Antennaria plantaginifolia), blue-stemmed goldenrod (Solidago caesia), wood lily (Lilium philadelphicum), and marginal wood fern (Dryopteris marginalis).
Diagnostic enriched-site species that differentiate this community from other rocky ridges include rock sandwort (Minuartia stricta), rusty woodsia (Woodsia ilvensis), ebony spleenwort (Asplenium platyneuron), stellate sedge (Carex radiata), blunt-lobed hepatica (Anemone americana), harebell (Campanula rotundifolia), wild licorice (Galium circaezans), basswood (Tilia americana), sugar maple, and white ash (Fraxinus americana). 

Variants:
Two variants are described.

1. Appalachian oak - hickory variant
   This variant is characterized by southern oaks (white, black, chestnut), hickories, and numerous species with southern distributions that do not reach central New Hampshire or the White Mountains including blunt-lobed woodsia (Woodsia obtusa), early buttercup (Ranunculus fascicularis), reflexed sedge (Carex retroflexa), headed sedge (Carex cephalophora), and Venus's looking-glass (Triodanis perfoliata).

2. Red oak variant
   This variant is more prevalent in central New Hampshire and the lower slopes and ridges in major southern valleys of the White Mountains. It lacks many or all of the southern species mentioned in the Appalachian oak - hickory variant. Rock sandwort (Minuartia stricta) and Douglas' knotweed (Polygonum douglasii) occur in a few examples in the White Mountains.


At least one occurrence of this community contains species characteristic of mafic “traprock” bedrock. Species here include rock spikemoss (Selaginella rupestris), slender gerardia (Agalinis tenuifolia), and native occurrences of field chickweed (Cerastium arvense). This site deserves further research. More northern examples of the community may exist but are not well documented.


Good examples of this community occur at West Rattlesnake Mtn. (Holderness), Daniels Mtn. (Hinsdale), Warwick Preserve (Westmoreland), Pawtuckaway State Park (Nottingham), Fall Mtn. (Walpole), and Harts Ledge (Bartlett).

Red oak - ironwood - Pennsylvania sedge woodland usually occurs as part of a larger rich Appalachian oak rocky woods system.


Red oak - ironwood - PA sedge woodland at Pawtuckaway State Park (photo by Ben Kimball for the NH Natural Heritage Bureau)
Red oak - ironwood - Pennsylvania sedge woodland at Pawtuckaway State Park (photo by Ben Kimball)

PA sedge woodland at Pawtukaway State Park (photo by Ben Kimball for the NH Natural Heritage Bureau)
Red oak - ironwood - Pennsylvania sedge woodland at Pawtuckaway State Park
(photo by Ben Kimball)

Red oak - ironwood - PA sedge woodland at Pawtuckaway State Park (photo by Ben Kimball for the NH Natural Heritage Bureau)
Red oak - ironwood - Pennsylvania sedge woodland at Middle Mountain
in Pawtuckaway State Park (photo by Ben Kimball)

Red oak - ironwood - Pennsylvania sedge woodland at Pawtuckaway State Park (photo by Dan Sperduto)
Red oak - ironwood - Pennsylvania sedge woodland at North Mountain
in Pawtuckaway State Park (photo by Dan Sperduto)



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